(19)
(11)EP 3 078 888 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
05.08.2020 Bulletin 2020/32

(21)Application number: 14867257.9

(22)Date of filing:  26.11.2014
(51)Int. Cl.: 
F01D 5/22  (2006.01)
F01D 11/08  (2006.01)
F01D 11/02  (2006.01)
F16J 15/447  (2006.01)
(86)International application number:
PCT/JP2014/081181
(87)International publication number:
WO 2015/083588 (11.06.2015 Gazette  2015/23)

(54)

SEAL STRUCTURE AND ROTARY MACHINE

DICHTUNGSSTRUKTUR UND DREHMASCHINE

STRUCTURE DE JOINT ET MACHINE ROTATIVE


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 03.12.2013 JP 2013250307

(43)Date of publication of application:
12.10.2016 Bulletin 2016/41

(73)Proprietor: Mitsubishi Hitachi Power Systems, Ltd.
Yokohama-shi, Kanagawa 220-8401 (JP)

(72)Inventors:
  • KUWAMURA, Yoshihiro
    Tokyo 108-8215 (JP)
  • MATSUMOTO, Kazuyuki
    Tokyo 108-8215 (JP)
  • OYAMA, Hiroharu
    Tokyo 108-8215 (JP)
  • TANAKA, Yoshinori
    Tokyo 108-8215 (JP)
  • NISHIKAWA, Toyoharu
    Tokyo 108-8215 (JP)
  • UEHARA, Hidekazu
    Tokyo 108-8215 (JP)
  • NISHIMOTO, Shin
    Tokyo 108-8215 (JP)

(74)Representative: Hoffmann Eitle 
Patent- und Rechtsanwälte PartmbB Arabellastraße 30
81925 München
81925 München (DE)


(56)References cited: : 
CN-U- 201 851 172
JP-A- 2005 180 278
JP-A- 2011 208 602
JP-A- 2012 072 689
JP-A- H11 148 307
JP-A- 2011 012 631
JP-A- 2011 208 602
US-A1- 2012 043 728
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    TECHNICAL FIELD



    [0001] The present invention relates to a seal structure which seals the gap between structures that rotate relative to each other in a rotary machine such as a steam turbine and a gas turbine, and to a rotary machine that is provided with this seal structure.

    BACKGROUND ART



    [0002] In a rotary machine such as a steam turbine and a gas turbine, there is used a non-contact type seal structure such as a labyrinth seal, in order to prevent leakage of a working fluid such as steam from a gap formed between the stationary side and rotor side.

    [0003] As a labyrinth seal there is known a step-type labyrinth seal in which, on an inner circumference of a casing that serves as an outer shell of a rotary machine, there are provided seal members such as seal fins that extend toward rotor blades, and there is provided a step-shaped shroud provided on the tip end of the rotor blades (for example, refer to JP 2006/104952 A).

    [0004] As shown in FIG. 7, a step-type labyrinth seal 102 includes; a plurality of seal fins 17, 18, and 19 that extend from a casing 10, and a step part 3 formed on a shroud 51 which is provided on the tip end part of a rotor blade 50. The labyrinth seal 102 is configured of an upstream side cavity 25 that is formed by a front-facing step, and a downstream side cavity 26 that is formed by a rear-facing step.

    [0005] Within the upstream side cavity 25 formed by a front-facing step, a leak jet SL which has traveled through an upstream gap mA between an upstream seal fin 17 and a base surface 4 of the shroud 51, forms a vortex B while colliding with an upstream side surface of the step part 3, thereby deflecting the leak jet SL. As a result, blow-by of a leak jet SL2 into an intermediate gap mB between an intermediate seal fin 18 and the step part 3 is suppressed and the amount of leakage is reduced.

    [0006] US 2012/0043728 A1 discloses a seal that is provided for preventing axial leakage through a radial gap between a stationary structure and a rotating structure. The radial gap is defined by an inner radial surface opposing an outer radial surface across the radial gap. The seal includes at least one land disposed on one of the inner radial surface and outer radial surface. At least one first tooth and at least one second tooth project from the other of the radial surfaces. The second tooth is shorter than the first tooth. At least one of the first tooth and second tooth, is configured to extend at an angle upstream. This angle is defined between a radial surface from which the first or second tooth projects and an upstream surface of the same tooth. The angle is less than or equal to about 80 degrees.

    [0007] JP H11 148307 A discloses a turbine moving blade that has a shroud formed integrally with a blade on its tip, and a casing surrounding the outer periphery of this moving blade is provided with plural fins axially. A step whose root part has a curved shape and height is larger than its curve radius is provided at a position sandwiched between an inlet side fin and an outlet side fin of the shroud on such moving blade. Therefore, when working fluid passes through an inter-blade flow passage of the moving blade, a flow enters the tip of the moving blade. Because this flow passes through a micro flow passage and then the flow's direction is forcibly changed to the radius direction by the curve surface of the root part, leak amount from the moving blade's tip can be reduced.

    [0008] CN201851172 U discloses a Brandon steam seal that comprises a rotor, a stator, a plurality of steam seal arc sections connected to the stator, a spring connected to each steam seal arc section for controlling a direct gear on the steam seal arc section to move away from the rotor, and at least one side gear fixed on the direct gear. The side gear is arranged on the direct gear of the steam seal arc section in the Brandon steam seal, so that the smooth flowing of the steam in a gap between the steam seal arc section and the rotor is stopped so as to reduce the flow speed of the steam in the gap between the steam seal arc section and the rotor and reduce the steam leakage volume.

    [0009] JP2011208602 discloses a turbine that includes a blade and a structure rotated relative to the blade through a clearance on the front end side of the blade. One of a front end portion of the blade and a portion of the structure corresponding to the front end portion includes a step section having a step surface and protruding to the other. The other includes a seal fin protruding with respect to the step section. A cavity is disposed between the front end portion of the blade and the portion of the structure. The cavity is formed between the seal fin and a partition opposed to the seal fin on the upstream side in a rotation axis direction of the structure. The seal fin includes a fin body forming a micro clearance between itself and the step section; and a space restriction section which restricts the space of the micro clearance on the upstream side in the rotation axis direction, and forms a small cavity between the cavity and the micro clearance.

    SUMMARY OF INVENTION


    PROBLEMS TO BE SOLVED BY THE INVENTION



    [0010]  On the other hand, referring to JP 2006/104952 A again, within the downstream side cavity 26 formed by a rear-facing step, the reattachment point of the leak jet SL2 which has traveled through the intermediate gap mB becomes unstable, and sealing performance becomes unstable. In particular, in the case where the reattachment point is positioned on the base surface 4 of the shroud 51, the flow rate of a leak jet SL3 traveling through a downstream gap mC becomes high, and the leakage amount increases.

    [0011] An object of the present invention is to provide a rotary machine that reduces the leak jet which leaks from the gap formed between the stationary side and the rotor side, to thereby stabilize sealing performance.

    MEANS FOR SOLVING THE PROBLEM



    [0012] This object is solved by a seal structure with the features of claim 1 and a rotary machine with the features of claim 2. According to a first aspect of the present invention, a seal structure is a seal structure that seals a gap between a first structure and a second structure which faces the first structure in a radial direction and rotates relative to the first structure about an axis, as defined in claim 1.

    [0013] According to the above configuration, a leak flow that has passed through the first gap is divided by the protrusion part into a first vortex and a second vortex, and the leak flow is restrained from being reattached on the base surface, thereby reducing the amount of leak flow traveling into the second gap. As a result, sealing performance can be stabilized.

    [0014] In the seal structure, the protrusion part is of a configuration such that, between a downstream side end part of the step surface and the second fin in the axial direction, and between the step surface and the other structure in the radial direction, there is provided a reattachment edge that extends in the circumferential direction and causes the leak flow to be reattached thereon.

    [0015] According to the above configuration, the leak flow that has passed through the first gap can be stably reattached on the reattachment edge of the protrusion part.

    [0016] In the seal structure, the protrusion part is a member that is connected to an upstream side surface of the second fin and that is of a cylindrical shape concentric with the axis, extending in between the reattachment edge and the second fin.

    [0017] According to the above configuration, the first vortex on the downstream side of the first fin becomes greater and the vorticity of the first vortex becomes lower, causing a rise in static pressure.

    [0018] As a result, a pressure difference between before and after the first fin becomes small. Thereby, the amount of leakage can be further reduced.

    [0019] Moreover, the present invention provides a rotary machine that is provided with the above seal structure.

    EFFECT OF THE INVENTION



    [0020] According to the present invention, the leak flow that has passed through the first gap is divided by the protrusion part into a first vortex and a second vortex, and the leak flow is restrained from being reattached on the base surface, thereby reducing the amount of leak flow traveling into the second gap. As a result, sealing performance can be stabilized.

    BRIEF DESCRIPTION OF THE DRAWINGS



    [0021] 

    FIG. 1 is a cross-sectional view showing a schematic configuration of a steam turbine according to a first illustrative example.

    FIG. 2 is an enlarged cross-sectional view of a relevant part of the steam turbine according to the first illustrative example.

    FIG. 3 is a schematic diagram for describing the behavior of leak jets and vortices in the seal structure of the first illustrative example.

    FIG. 4 is a diagram for describing in detail the behavior of a leak jet passing through a downstream gap between a downstream seal fin and a base surface in the seal structure of the first illustrative example.

    FIG. 5 is a schematic diagram for describing the behavior of leak jets and vortices in a seal structure of an embodiment of the present invention.

    FIG. 6 is a schematic diagram for describing the behavior of leak jets and vortices in a seal structure of a second illustrative example.

    FIG. 7 is a schematic diagram for describing the behavior of leak jets and vortices in a conventional annular grooved seal structure.


    MODES FOR CARRYING OUT THE INVENTION


    (First Illustrative Example)



    [0022] Hereinafter, a steam turbine which is a rotary machine of a first illustrative example, not forming part of the claimed invention, but useful for understanding the invention, is described based on the drawings.

    [0023] As shown in FIG. 1, a steam turbine 1 of the present illustrative example is provided with: a casing 10 (structure), a rotation shaft 30 that is provided rotatably within the casing 10, and that transmits power to a machine such as a power generator (not shown in the figure), turbine vanes 40 held on the casing 10, turbine blades 50 provided on the rotation shaft 30, and a bearing part 60 that supports the rotation shaft 30 so as to be rotatable about the axis.

    [0024] Steam S is introduced via a steam supply pipe 20 connected to a steam supply source (not shown in the figure), from a main intake port 21 formed in the casing 10, and is discharged from a steam discharge pipe 22 connected to the downstream side of the steam turbine 1.

    [0025] The turbine vanes 40 and the turbine blades 50 are blades that extend in the radial direction of the axis O. The casing 10 is a structure that the turbine blades 50 rotate therein relative to about the axis O.

    [0026] The interior space of the casing 10 is sealed airtight. The casing 10 is a flow passage of steam S. On the inner wall surface of the casing 10 there are tightly fixed ring-shaped partition plate outer rings 11, into which the rotation shaft 30 is to be inserted.

    [0027] The bearing part 60 is provided with a journal bearing device 61 and a thrust bearing device 62, and it rotatably supports the rotation shaft 30.

    [0028] The turbine vanes 40 extend from the casing 10 toward the inner circumferential side and form a group of ring-shaped turbine vanes, in which a number of the turbine blades are arranged in a radial manner so as to surround the rotation shaft 30. The several turbine vanes 40 are held by the partition plate outer rings 11 respectively.

    [0029] The group of ring-shaped turbine vanes including the several turbine vanes 40 are formed in several positions while having intervals therebetween in the axial direction of the rotation shaft 30 (hereunder, referred to simply as the axial direction). These several turbine vanes 40 convert pressure energy of steam S into velocity energy, and cause it to flow into the turbine blades 50 adjacent thereto on the downstream side.

    [0030] The turbine blades 50 are tightly fitted to the outer circumference part of the rotation shaft main body 31 of the rotation shaft 30. The turbine blades 50, on the downstream side of each of the ring-shaped turbine vanes, are arranged in a radial manner at several positions so as to form a group of ring-shaped turbine blades.

    [0031] The ring-shaped turbine vane group and the ring-shaped turbine blade group are such that one set of each serves as one stage. Among these, the tip end parts of the turbine blades 50 on the final stage are such that the tip end parts of the turbine blades adjacent to each other in the circumferential direction of the rotation shaft 30 (hereunder, referred to simply as circumferential direction) are connected to each other, and are referred to as a shroud 51.

    [0032] As shown in FIG. 2, on the downstream side in the axial direction of the partition plate outer ring 11, there is formed a cylindrical annular groove 12, in which the diameter increases from the inner circumference part of the partition plate outer ring 11, and the inner circumferential surface of the casing 10 serves as a bottom surface 13 (opposing surface). In the annular groove 12 there is accommodated the shroud 51, and the bottom surface 13 opposes the shroud 51 via a gap Gd in the radial direction.

    [0033] The shroud 51 is provided with a step part 3 which is formed in a step shape and protrudes from an axially center portion of the shroud 51. Specifically, the surface of the shroud 51 on the radially outer circumferential side has; a base surface 4 (tip end surface), and the step part 3 that forms a step surface 5 protruding from the base surface 4 toward the outer circumference side in the radial direction.

    [0034] On the bottom surface 13 there are provided three seal fins 17, 18, and 19 respectively extending in the radial direction toward the shroud 51. The seal fins 17, 18, and 19 respectively extend from the bottom surface 13 to the inner circumferential side toward the shroud 51, and extend in the circumferential direction.

    [0035] Specifically, the upstream seal fin 17 protrudes toward the base surface 4 on the upstream side of the step part 3. The intermediate seal fin 18 (first fin) protrudes toward the step surface 5 of the step part 3. The downstream seal fin 19 (second fin) protrudes toward the base surface 4 on the downstream side of the step part 3. The intermediate seal fin 18 is formed so that the length thereof in the radial direction is shorter than that of the upstream seal fin 17 and the downstream seal fin 19.

    [0036] That is to say, in the gap Gd between the casing 10 and the turbine blades 50 of the present illustrative example, there is provided a seal structure 2, which is a step-type labyrinth seal.

    [0037] These seal fins 17, 18, and 19 form minute gaps m at the space with respect to the shroud 51. Hereinafter, the gap between the upstream seal fin 17 and the base surface 4 is referred to as an upstream gap mA, the gap between the intermediate seal fin 18 and the step surface 5 is referred to as an intermediate gap mB (first gap), and the gap between the downstream seal fin 19 and the base surface 4 is referred to as a downstream gap mC (second gap).

    [0038] The respective dimensions of the minute gaps m (mA through mC) take into consideration the amount of thermal expansion of the casing 10 and the turbine blade 50, as well as the amount of centrifugal expansion of the turbine blade 50. The respective dimensions of the minute gaps m (mA through mC) are set within a range where the seal fins 17, 18, and 19 do not to come in contact with the turbine blades 50.

    [0039] In the gap Gd, an upstream side cavity 25 and a downstream side cavity 26 are formed by the annular groove 12, the shroud 51, and the seal fins 17, 18, and 19. The positions of the seal fins 17, 18, and 19 in the axial direction are appropriately set according to the behavior of the leak jets and vortices within these cavities 25 and 26.

    [0040] On the upstream side of the downstream seal fin 19 there is integrally attached a protrusion 7 (protrusion part). The protrusion 7 is a solid member, the sectional shape of which is rectangular when viewed from the circumferential direction, and it extends in the circumferential direction along with the downstream seal fin 19.

    [0041] The protrusion 7 has a circular surface 8, which is oriented orthogonal to the axial direction on the upstream side of the downstream seal fin 19, and a cylindrical surface 9, which is of a cylinder-shaped surface concentric with the axis, and which extends in the circumferential direction while being orthogonal to the circular surface 8. The ridge line at which the circular surface 8 and the cylindrical surface 9 intersect with each other, serves as a reattachment edge 15. In other words, the circular surface 8 and the cylindrical surface 9 are surfaces that determine the position of the reattachment edge 15.

    [0042] The circular surface 8 is positioned in the axial direction between the downstream side end part of the step surface 5 and the downstream seal fin 19. Specifically, the circular surface 8 is arranged based on the position of the reattachment edge 15, which is determined by means of a method described later.

    [0043] The cylindrical surface 9 is positioned in the radial direction between the step surface 5 and the bottom surface 13 of the annular groove 12. Specifically, the cylindrical surface 9 is arranged based on the position of the reattachment edge 15.

    [0044] Here, an operation of the steam turbine 1 that is configured in the manner described above is described.

    [0045] First, steam S flows into the interior space of the casing 10 via the steam supply pipe 20, from a steam supply source such as a boiler (not shown in the figure).

    [0046] The steam S which has flowed into the interior space of the casing 10 travels sequentially through the ring-shaped turbine vane group and the ring-shaped turbine blade group in each stage.

    [0047] In the ring-shaped turbine vane group of each stage, the steam S gets the circumferential velocity component thereof increased while traveling through the turbine vanes 40. Steam SM which is the majority portion of this steam S (refer to FIG. 2) flows into the spaces between the turbine blades 50, and the energy of the steam SM is converted into rotational energy thereby causing the rotation shaft 30 to rotate.

    [0048] On the other hand, a leak jet SL (leakage flow, or leak flow), which is a portion of the steam S (for example, only a few percent approximately), after having flowed out from the turbine vanes 40, flows into the annular groove 12 while maintaining its strong circumferential direction component (swirl flow).

    [0049] As shown in FIG. 3, the leak jet SL collides with the upstream-side-facing surface of the step part 3 and is deflected while forming a vortex B1. As a result, the amount of leakage of the leak jet SL into the intermediate gap mB is reduced.

    [0050] A leak jet SL2 that has passed through the intermediate gap mB stably becomes reattached on the reattachment edge 15 of the protrusion 7 provided on the downstream side. That is to say, the reattachment point of the leak jet SL2 is controlled, and a vortex B3 (first vortex) is formed in a space surrounded by the leak jet SL, the intermediate seal fin 18, and the circular surface 8, while a vortex B4 (second vortex) is formed in a space surrounded by the leak jet SL2, the cylindrical surface 9, and the base surface 4. In other words, the leak jet SL2 is divided by the protrusion 7 into the vortex B3 along the intermediate seal fin 18 and the vortex B4 along the downstream seal fin 19.

    [0051] Thereby, the leak jet SL2 is restrained from being reattached on the bottom surface 13 and the base surface 4 (step part 3).

    [0052] As shown in FIG. 4, the vortex B4 becomes a flow that opposes the leak jet SL3 which collides with the downstream seal fin 19 and passes through the downstream gap mC, and therefore the leak jet SL3 is reduced.

    [0053] Next, a method of determining the position of the reattachment edge 15 is described.

    [0054] The position of the reattachment edge 15 is set to a position where the leak jet SL2 having passed through the intermediate gap mB is likely to be reattached. The reattachment edge 15 of the present illustrative example is set in the close vicinity of a midpoint, in the axial direction, between the downstream side end of the step surface 5 and the downstream seal fin 19, and is positioned in the radial direction, slightly to the radially outer circumferential side of the step surface 5.

    [0055] The position of the reattachment edge 15 is appropriately calculated by means of analysis using computational fluid dynamics (CFD), according to the specifications of the steam turbine 1 such as the clearance between the shroud 51 and the bottom surface 13, and the flow rate of swirl flow flowing into the cavities 25 and 26.

    [0056] When the steam turbine 1 is operating, a difference in the expansion amount of each part occurs due to the difference in materials used in the respective parts that constitute the steam turbine 1, and/or the difference in temperatures to which the respective parts are exposed. As a result, the relative positions between the rotation shaft 30 and the casing 10 in the axial direction change.

    [0057] The reattachment edge 15 is set so that even in this type of case where the relative positions between the rotation shaft 30 and the casing 10 have changed, the reattachment edge 15 will not be in a position where it opposes the step surface 5 in the radial direction. In other words, the protrusion 7 is set so that the reattachment edge 15 always opposes the base surface 4 in the radial direction.

    [0058] According to the illustrative example above, the leak jet SL2 that has passed through the intermediate gap mB stably becomes reattached on the reattachment edge 15 of the protrusion 7. That is to say, the leak jet SL2 is restrained from being reattached on the base surface 4, and the flow of the leak jet SL3 traveling into the downstream gap mC is reduced, thereby enabling stable sealing performance. In particular, it is possible to reduce the flow rate of the leak jet SL3 by means of the vortex B4, which is formed as a result of the leak jet SL2 reattaching on the reattachment edge 15 of the protrusion 7.

    [0059] The circular surface 8 of the present illustrative example is formed so that the principal surface thereof is oriented orthogonal to the axis O. However, it is not limited to this as long as the set position of the reattachment edge 15 can be maintained. For example, the circular surface 8 may be of a shape that slopes toward the upstream side with approach to the radially outer circumferential side.

    [0060] Similarly, the cylindrical surface 9 may also be of a shape that slopes toward the radially inner circumferential side with approach to the downstream side.

    [0061] Moreover, the protrusion 7 may be of a hollow structure, rather than being a solid structure.

    (Embodiment)



    [0062] Hereinafter, a seal structure of a steam turbine of an embodiment of the present invention is described, based on the drawings. In the present embodiment, points that differ from the first illustrative example described above are mainly described, and descriptions of similar portions are omitted.

    [0063] As shown in FIG. 5, a protrusion 7B of a seal structure 2B of the present embodiment is a cylindrical member that protrudes from an upstream side surface 19a of a downstream seal fin 19 toward the upstream side, and that extends in the circumferential direction. In other words, the protrusion 7B is a cylindrical member being concentric with the axis O (refer to FIG. 1), that is connected to the upstream side surface 19a of the downstream seal fin 19, and extends between a reattachment edge 15 and the downstream seal fin 19.

    [0064] A leak jet SL2 that has passed through the intermediate gap mB becomes reattached on the reattachment edge 15, which is the most upstream side end part of the protrusion 7B, and a large vortex B5 is generated on the downstream side of the intermediate seal fin 18.

    [0065] According to the embodiment above, the vortex B5 on the downstream side of the intermediate seal fin 18 becomes larger and the vorticity of the vortex B5 becomes lower, causing a rise in static pressure. Hence the pressure difference between before and after the intermediate seal fin 18 becomes small. As a result, the amount of leakage can be further reduced, in addition to the effect of the steam turbine 1 of the first illustrative example.

    (Second Illustrative Example)



    [0066] Hereinafter, a seal structure of a steam turbine of a second illustrative example of the present invention is described, based on the drawings. In the present embodiment, points that differ from the first illustrative example described above are mainly described, and descriptions of similar portions are omitted.

    [0067] As shown in FIG. 6, a protrusion 7C of a seal structure 2C of the present illustrative example is a disk-shaped member that is arranged between an intermediate seal fin 18 and a downstream seal fin 19, and that extends in the radial direction from a bottom surface 13 of an annular groove 12 toward a base surface 4 of the shroud 51. In other words, the protrusion 7C of the present illustrative example is a disk-shaped member that extends in between the bottom surface 13 of the annular groove 12 and a reattachment edge 15.

    [0068] A leak jet SL2 that has passed through the intermediate gap mB becomes reattached on the reattachment edge 15, which is the most upstream side end part of the protrusion 7C, and a vortex B6 is further generated on the downstream side of the protrusion 7C.

    [0069] According to the illustrative example above, the vortex B6 is generated on the downstream side of the protrusion 7C, and kinetic energy is dissipated into heat due to the mixing loss within the vortex, resulting in a total pressure loss. As a result, the amount of leakage can be further reduced in addition to the effect of the first illustrative example.

    [0070] The illustrative examples and the embodiment of the present invention have been described with reference to the drawings. However, the respective configurations in the respective embodiment and combinations thereof are merely examples, and addition, omission, replacement, and/or other modifications may be made to the configuration within the scope of the appended claims. Moreover, the present invention is not to be considered limited by the embodiments, but only by the scope of the appended claims.

    [0071] For example, in the embodiment above, a labyrinth seal is configured with a step part 3 of the shroud 51 provided on the tip end side (rotation side) of the turbine blade 50, and seal fins 17, 18, and 19 provided on the bottom surface 13 of the annular groove 12 (stationary side). However, the configuration is not limited to this. For example, the configuration may be such that seal fins are provided on the turbine blade side, which is the rotation side, and a step part is provided on the annular groove 12 (casing), which is on the stationary side.

    [0072] Moreover, the invention may be applied to a labyrinth seal that seals the gap between the casing and the rotation shaft with no turbine blades provided thereon. For example, the invention may be applied to a shaft seal between a turbine casing and rotors, a seal between blades and a casing of an axial flow compressor, and a seal between a centrifugal compressor casing and an impeller.

    [0073] In other words, the seal structure of the embodiment above may be applied to a rotary machine that is provided with: a second structure that faces a first structure in the radial direction via a gap and rotates relative to the first structure about the axis; and a plurality of seal fins that are provided on either one of the first structure and the second structure, and that protrude toward the other structure and form minute gaps at the space with respect to the other structure while being provided at intervals in the axial direction.

    INDUSTRIAL APPLICABILITY



    [0074] According to the seal structure, a leak flow that has passed through the first gap is divided by the protrusion part into a first vortex and a second vortex, and the leak flow is restrained from being reattached on the base surface, thereby reducing the amount of leak flow traveling into the second gap. As a result, sealing performance can be stabilized.

    DESCRIPTION OF REFERENCE SYMBOLS



    [0075] 
    1
    Steam turbine (rotary machine)
    2, 2B, 2C
    Seal structure
    3
    Step part
    4
    Base surface
    5
    Step surface
    7
    Protrusion (protrusion part)
    8
    Circular surface
    9
    Cylindrical surface
    10
    Casing (first structure, second structure)
    11
    Partition plate outer ring
    12
    Annular groove
    13
    Bottom surface
    15
    Reattachment edge
    17
    Upstream seal fin
    18
    Intermediate seal fin (first fin)
    19
    Downstream seal fin (second fin)
    25
    Upstream side cavity
    26
    Downstream side cavity
    30
    Rotation shaft
    31
    Axis main body
    32
    Disk
    40
    Turbine Vane (blade)
    50
    Turbine blade (blade)
    51
    Shroud (first structure, second structure)
    60
    Bearing part
    61
    Journal bearing device
    62
    Thrust bearing device
    B3
    Vortex (first vortex)
    B4
    Vortex (second vortex)
    Gd
    Gap
    mA
    Upstream gap
    mB
    Intermediate gap (first gap)
    mC
    Downstream gap (second gap)
    O
    Axis
    SL
    Leak jet (leak flow)



    Claims

    1. A seal structure (2) that seals a gap (Gd) between a first structure (10,51) and a second structure (10,51) which faces the first structure in a radial direction and rotates relative to the first structure about an axis (O), wherein
    one (51) of the first structure (10,51) and the second structure (10,51) has base surfaces (4) and a step surface (5) that protrudes toward the other side from the base surfaces (4),
    wherein the other (10) of the first structure (10,51) and the second structure (10,51) is provided with:

    a first fin (18) which extends toward the step surface (5) and forms a first gap (mB) at a space with respect to the step surface (5), and

    a second fin (19) that, on a downstream side of the first fin (18), extends toward the base surface (4) and forms a second gap (mC) at a space with respect to the base surface (4), characterized in that

    the other structure (10) of the first structure (10,51) and the second structure (10,51) further comprises a protrusion part (7B) that is disposed between the first fin (18) and the second fin (19) and that divides a leak flow (SL) which has passed through the first gap (mB), into a first vortex (B5) along the first fin (18) and a second vortex (B4) along the second fin (19),

    the protrusion part (7B) includes a reattachment edge (15) that extends in a circumferential direction and causes the leak flow (SL) to be reattached thereon, wherein the reattachment edge (15) is provided in a position between a downstream side end part of the step surface (5) and the second fin (19) in the axial direction, and between the step surface (5) and the other structure (10) in the radial direction, and

    wherein the protrusion part (7B) is a member that is connected to an upstream side surface of the second fin (19) and that is of a cylindrical shape concentric with the axis (O), extending in the circumferential direction between the reattachment edge (15) and the second fin (19), wherein

    the reattachment edge (15) is the most upstream side end part of the protrusion (7B) and opposes the base surface (4) at the downstream side with respect to the step surface (5) in the radial direction along with the reattachment edge (15) not being in a position where it opposes the step surface (5) in the radial direction.


     
    2. A rotary machine (1) comprising a seal structure (2) according to Claim 1.
     


    Ansprüche

    1. Dichtungsstruktur (2), die einen Spalt (Gd) zwischen einer ersten Struktur (10,51) und einer zweiten Struktur (10,51), die der ersten Struktur in einer radialen Richtung zugewandt ist und relativ zu der ersten Struktur um eine Achse (O) dreht, abdichtet, wobei
    eine (51) der ersten Struktur (10,51) und der zweiten Struktur (10,51) Basisflächen (4) und eine Stufenfläche (5), die von den Basisflächen (4) zu der anderen Seite ragt, aufweist,
    wobei die andere (10) der ersten Struktur (10,51) und der zweiten Struktur (10,51) versehen ist mit:

    einer ersten Rippe (18), die sich zu der Stufenfläche (5) erstreckt und einen ersten Spalt (mB) mit einem Abstand in Bezug auf die Stufenfläche (5) bildet, und

    einer zweiten Rippe (19), die sich, an einer stromabwärts liegenden Seite der ersten Rippe (18), zu der Basisfläche (4) erstreckt und einen zweiten Spalt (mC) mit einem Abstand in Bezug auf die Basisfläche (4) bildet, dadurch gekennzeichnet, dass

    die andere Struktur (10) der ersten Struktur (10,51) und der zweiten Struktur (10,51) weiter ein vorstehendes Teil (7B) umfasst, das zwischen der ersten Rippe (18) und der zweiten Rippe (19) angeordnet ist und das einen Leckstrom (SL), der durch den ersten Spalt (mB) gegangen ist, in einen ersten Wirbel (B5) entlang der ersten Rippe (18) und einen zweiten Wirbel (B4) entlang der zweiten Rippe (19) teilt,

    das vorstehende Teil (7B) eine Wiederanlegungskante (15) beinhaltet, die sich in einer Umfangsrichtung erstreckt und ein Wiederanlegen des Leckstroms (SL) daran bewirkt, wobei die Wiederanlegungskante (15) an einer Position zwischen einem stromabwärts liegenden Seitenendteil der Stufenfläche (5) und der zweiten Rippe (19) in der axialen Richtung und zwischen der Stufenfläche (5) und der anderen Struktur (10) in der radialen Richtung vorgesehen ist, und

    wobei das vorstehende Teil (7B) ein Element ist, das mit einer stromaufwärts liegenden Seitenfläche der zweiten Rippe (19) verbunden ist und das von zylindrischer Form konzentrisch mit der Achse (O) ist, wobei es sich in der Umfangsrichtung zwischen der Wiederanlegungskante (15) und der zweiten Rippe (19) erstreckt, wobei

    die Wiederanlegungskante (15) das am weitesten stromaufwärts liegende Seitenendteil des vorstehenden Teils (7B) ist und der Basisfläche (4) an der stromabwärts liegenden Seite in Bezug auf die Stufenfläche (5) in der radialen Richtung gegenüberliegt, einhergehend damit, dass die Wiederanlegungskante (15) nicht in einer Position ist, wo sie der Stufenfläche (5) in der radialen Richtung gegenüberliegt.


     
    2. Drehmaschine (1), umfassend eine Dichtungsstruktur (2) nach Anspruch 1.
     


    Revendications

    1. Structure de joint (2), qui rend étanche un trou (Gd) entre une première structure (10, 51) et une seconde structure (10, 51) qui est tournée vers la première structure dans une direction radiale, et qui tourne par rapport à la première structure autour d'un axe (O), dans laquelle
    une (51) de la première structure (10, 51) et de la seconde structure (10, 51) présente des surfaces de base (4) et une surface marche (5) qui fait saillie vers l'autre côté des surfaces de base (4),
    dans laquelle l'autre (10) de la première structure (10, 51) et de la seconde structure (10, 51) est pourvue :

    d'une première ailette (18) qui s'étend vers la surface marche (5) et forme un premier trou (mB) au niveau d'un espace par rapport à la surface marche (5), et

    d'une seconde ailette (19) qui, sur un côté en aval de la première ailette (18), s'étend vers la surface de base (4) et forme un second trou (mC) au niveau d'un espace par rapport à la surface de base (4), caractérisée en ce que

    l'autre structure (10) de la première structure (10, 51) et de la seconde structure (10, 51) comprend en outre une pièce en saillie (7B), qui est disposée entre la première ailette (18) et la seconde ailette (19), et qui sépare un écoulement de fuite (SL) qui a traversé le premier trou (mB) en un premier tourbillon (B5) le long de la première ailette (18) et en un second tourbillon (B4) le long de la seconde ailette (19),

    la pièce en saillie (7B) inclut une bordure de rattachement (15) qui s'étend dans une direction circonférentielle et amène l'écoulement de fuite (SL) à être rattaché sur celle-ci, dans laquelle la bordure de rattachement (15) est pourvue dans une position entre une partie d'extrémité latérale en aval de la surface marche (5) et la seconde ailette (19) dans la direction axiale, et entre la surface marche (5) et l'autre structure (10) dans la direction radiale, et

    dans laquelle la pièce en saillie (7B) est un élément qui est connecté à une surface de côté en amont de la seconde ailette (19) et qui est de forme cylindrique concentrique à l'axe (O), s'étendant dans la direction circonférentielle entre la bordure de rattachement (15) et la seconde ailette (19), dans laquelle

    la bordure de rattachement (15) est la partie d'extrémité latérale la plus en amont de la saillie (7B) et est à l'opposé de la surface de base (4) au niveau du côté en aval par rapport à la surface marche (5) dans la direction radiale, avec la bordure de rattachement (15) n'étant pas dans une position où elle est à l'opposé de la surface marche (5) dans la direction radiale.


     
    2. Machine rotative (1) comprenant une structure de joint (2) selon la revendication 1.
     




    Drawing


















    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description